This invention relates to a credit card, to a process and an electrically operated appliance for manufacturing said credit card, and to an electrically operated appliance for marking said credit card in order to make deductions from a credit represented by said card.
Known value and/or credit cards comprise magnetic strips and can be inserted into writing and reading appliances in order to read the remaining credit, to make deductions and to write the credit which remains after the deduction. Such credit cards often contain visible markings, which indicate the remaining credit to the user. These systems have the disadvantage that all functions, such as detection of remaining credit, recognition of code, deduction and visible marking, can be performed only by different processes, which are technically difficult and expensive.
It is an object of the invention to provide an appliance for deducting value units on a credit card. By means of such an appliance the charges involved in the use of servies or the delivery of merchandise, such as copies from an automatic copier, should be automatically deducted. An automatic deduction should be permitted with a data carrier and a reading and writing appliance which involve only a minimum expenditure so that the system can be used also for transactions which involve only a relatively small value so that the use of expensive appliances or processes would not be justified.